.flip-clock {
    display: flex;
    justify-content: center;
    align-items: center;
    font-family: 'Arial', sans-serif;
    background-color: rgba(0, 0, 0, 0.5);
    padding: 20px;
    border-radius: 10px;
}

.flip-unit {
    margin: 0 2px;
}


.flip-card {
    position: relative;
    width: 60px;
    height: 90px;
    perspective: 1000px;
    background-color: transparent;
}

.front,
.back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 48px;
    color: #fff;
    background-color: #333;
    border-radius: 5px;
    transition: transform 0.5s;
}

.front {
    z-index: 2;
}

.back {
    transform: rotateX(-180deg);
}

.flip-card.flip .front {
    transform: rotateX(180deg);
}

.flip-card.flip .back {
    transform: rotateX(0deg);
}

.separator {
    font-size: 48px;
    color: #fff;
    margin: 0 5px;
}


@media (max-width: 768px) {
    .flip-card {
        width: 40px;
        height: 60px;
        font-size: 32px;
    }

    .separator {
        font-size: 32px;
    }
}